Fluid actuated downwell pump



P. S- BLOUDOFF FLUID ACTUATED DOWNWELL PUMP Dec. 15, 1964 Filed March20, 1962 FILTERS INVENTOR. PETER S. BLOUDOFF BY 2 2 ATTORNEYS 3,lhl,ldPatented Dec. 15, 1964 3,161,140 FLUID ACTUATED DOWNWELL PUMP Peter S.Bloudoii, Whittier, Califl, assignor to Armco' Steel Corporation,Middletown, Ohio, a corporation of Uhio Filed Mar. 20, 1962, Ser. No.181,0% 2 Ciaims. (Cl. 1ti346) This invention relates to fluid actuateddownwell pumps for oil wells and is particularly directed to a structurethat is especially adapted for use in wells producing oil that carries ahigh solids content.

It has heretofore been recognized that fluid actuated downwell pumps areoperable only with difiiculty in wells where the production fluidcontains a high percentage of paraffin. These pumps are operated byclean oil which is usually conveyed from the surface through a smalldiameter string of tubing known as a macaroni string, and-the productionfluid and spent power oil are returned to the surface through theannulus between the well tubing and the macaroni string. In someinstances, of course, separate return strings are provided for spentpower oil and for production fluid. As the production fluid approachesthe surface, parafiin which will remain in solution at the temperatureof the system adjacent the pump condenses out of solution and adheres tothe inner walls of the tubing and the outside walls of the macaronistring. When the accumulation is such that the passage is severelyrestricted, the pump must be shut down, the macaroni string pulled andcleaned and a swab sent down the tubing to remove the parafiin from itswalls. This is a time consuming and costly operation.

In the installation according to the present invention, power oil ispumped down the annulus between the macaroni string the tubing and theproduction is forced up through the macaroni string. The invention isespecially concerned with means to remove paraifin and othercontaminating materials without pulling the macaroni string. Means areprovided to clean the entire system if neces sary, or to clean themacaroni alone. This latter means includes a valve provided in thefitting which attaches the pump to the macaroni string, which valve isnormally closed, but can be opened when the circulation in the well isreversed. By this simple expedient, the areas which collect paraifinduring production can be cleaned without pulling the pump from the wellmerely by inserting a soluble plug in the macaroni string, forcing itdown towards the pump and removing the accumulated paraflin out throughthe annulus, the circulation of fluid being thus reversed during thecleaning operation. To complete the cleaning operation, if desired, thepump can be raised from its seat in the well fittings, and clean fluidcirculated in the system. During this circulation, clean power oilpasses through the pump in a direction normally taken by pumpedproduction fluid. The clean power oil is prevented from going out intothe formation by the conventional standing valve assembly which is installed below the pump.

The installation according to the present invention does not involve thewell casing in any way, nor does it require the separate side stringsfrequently associated with so called free pump installations. Thepresent invention is applicable to pumps falling under the category offixed pump" installations, and is especially advantageous for so-ealledslim-hole completions in which the diameter of thestring in which thepump isseated may be less than three inches. i

A well installation according to the present invention is showndiagrammatically in the accompanying drawings, in which:

FIG. 1 is a central, longitudinal, sectional view, with parts brokenaway and with other parts shown in full lines of an apparatus accordingto the invention in its normal operating position;

FIG. 2 is a fragmentary view of the parts shown in FIG. 1 indicating thecirculation of fluid and the position oi the parts during cleaning; and

FIG. 3 is another fragmentary and diagrammatic view showing the positionof the parts during an additional cleaning step.

Referring to the drawings, and particularly to FIG. 1., the presentinvention is shown in conjunction with a well having an outer slimcasing string it) carrying certain conventional bottom hole elementssuch as a screen 12 adjacent the producing formation. A pump anchorpacker 14 is disposed within the string 10 and a standing valve 16 isattached to the anchor in a known manner. The valve it? opens during thenormal suction stroke of the pump and closes during the dischargestroke.

A fiuid actuated downwell pump unit 20 may also be a conventional unitand may be constructed and operated as described in Brennan and BloudoffPatent No. 2,921,531, issued January 19, 1960. The pump unit is seatedin the packer 14- during normal operation as shown in FIG. 1. The pumpwill he treated herein as a unit which is attached to the lower end of amacaroni string 22. In most installations the macaroni is used to carrypower oil to the pump, but in the present instance the normalcirculation is such that power oil flows down the annulus 24 between themacaroni string 22 and the casing it), and returns to the surface in themacaroni string 22. A supply connection .26 crosses over from the annulus 24 to the inlet of the pump engine to cause reciprocation of theengine and pump pistons as shown in the Brennan and Bloudoil patentabove mentioned.

A lower pump inlet valve 28 is shown in dotted lines in FIG. 1, and thedischarge of production fluid from the pump is through a peripheralseries of discharge ports 3h into the annulus 32 between the exterior ofthe pump engine cylinders and the pump jacket which is designated 34.The spent power oil is discharged through a separate series of spacedports 36 into the same annulus, and the mingled power oil and productionfluid goes to the surface through the macaroni 22.

The surface equipment used with the present invention and by which poweroil is put under pressure and circulated is shown very diagrammaticallyin FIG. 1. A conventional triplex pump 38 takes power oil from a sump40, increases its pressure to several thousand pounds and discharges itinto a power oil supply conduit 42, through a four-way valve 44 to aline 45 leading to the annulus 24 for circulation to the pump. Thereturned fluid, comprising comingled spent power oil and production oil,flows from the macaroni string 22 into a line 46, through 'a shut-offvalve 47 and into a filter 43. A portion of this returned oil is led toa storage line or tank (not shown) and another portion is filtered andcleaned to be used as power oil. The cleaned oil is taken to sump 40through a shut-off valve 49. In accordance with the requirements of thepresent invention which will become apparent, provision is made forreversing the circulation and discharging power oil from the pump 38into the macaroni string 22 and for taking fluid from the annulus 24back to the filters 48. For this purpose the fourway valve 44 isprovided with ports which will connect the pump discharge line 42 to theline 46 ahead of the shut-off valve 47, while a second reversible valve59, normally closed during operation, is opened to connect a by-passline 52 between the'macaroni string and the filters 48.

In many wells the production fluid carries a high percentage of paratlinand similar solids which remain in solution at the temperatures existingat the producting horizon but which condense out and accumulate on theWalls of the conduit in which it flows to the surface. The accumulationbecomes troublesome after a period of time and so restricts the flowthat it must be removed. In many instances removal can be accomplishedonly by pulling the pump and scraping the accumulated solids away. Thisis particularly true if the return conduit is annular. The presentinvention is particularly directed to a simple and inexpensive expedientby which solids removal may be accomplished quickly and without pullingthe pump and disassembling the macaroni.

The present invention provides a valve 55 preferably carried at theconnection between the pump unit and the macaroni string 22 and openingin the direction of the power oil annulus 24 which may be operated fromthe surface. In the preferred form, the valve 55 is a simple check valvewhich opens whenever the pressure in the macaroni string 22 predominatesover the pressure in the annulus 24. During normal operation the checkvalve 55 remains seated because the pressure of power oil in the annulus24 is greater than the discharge pressure of the pump unit into themacaroni 22. However, when the circulation is reversed so that power oilis put into the macaroni string and fluid exhausted from the annulus 24,valve 55 will open.

At the well head, provision is made for a removable cap 57 or any othersuitable expedient by which the interior of the macaroni string becomesaccessible. A plug of parafiin or other soluble material can be placedthrough the opening of the cap 57, into the macaroni string. When thecirculation is reversed so that power oil flows from the four-way valve44 and into the macaroni string 22, the soluble plug can be circulateddown the macaroni string, scraping paraffin from the interior of thewalls of the macaroni string as it goes and forcing the accumulatedsolids into the annulus 24 through the now opened check valve 55. If thesoluble plug is of paraffin or similar material, it will dissolve at thehigh temperatures encountered towards the lower end of the macaronistring where there is no accumulation of solids so that the plug itselfnever reaches the check valve 55. By this simple expedient, accumulatedsolids may be scraped from the interior of the macaroni string 22without removing the pump from the well or without in any waydisassembling the macaroni and associated elements. This circulation isindicated in FIG. 2, the soluble plug being designated 59 in thisfigure. During this cleaning operation, the four-way valve 44 is turnedto connect power oil supply conduit 42 with the line 46 and thereversing valve 50 is turned at the same time to connect line 45 fromthe annulus 24 into the by-pass 52 leading to the filters 48, the fluidfrom the annulus 24 being thus at low exhaust pressure at this point.Valve 47 will be shut 011 so that power oil pressure does not appear atthe filters.

By reversing the circulation as above described, accumulated solids areremoved from the interior of the macaroni string. If it is desired tofurther clean the well and particularly to remove accumulated solidsfrom the pump itself, the present invention provides means to raise thepump unit from its seat as indicated in FIG. 3. Since the pump isnormally seated on the anchor 14, raising the pump from the anchor willpermit power oil from the annulus 24 to enter through the pump inletvalve 28 and circulate through the pump to carry ahead of it any sand,paraflin or accumulated materials. These materials are forced outthrough the pump discharge ports 30 into the annulus 32 between the pumpcylinder and pump jacket 34 to return to the surface in the macaronistring 22. This circulation in the normal direction does not operate thepump engine, however, because the pressure at the discharge ports of thepump is essentially the same as the pressure at the engine inlet port orcrossover 26. The pump with which the present invention is particularlyapplicable operates on a pressure differential principle and if there isinsufficient pressure differential between the upper and lower faces ofthe pump piston the pump engine will not reciprocate. Thus the pressureof power oil at the inlet valve 28 simply raises the valve from itsseat, causing the clean oil to pass through the pump in the directionnormally taken by production fluid. The power oil cleans out the pumpitself, and passes all of the accumulated contaminating material back tothe surface. The valve 55 remains closed during this cleaning step, asdoes the well standing valve 16.

Tubing elevators which are Well adapted to move the pump unit from theseated position on the anchor 14 to the raised positions shown in FIG. 3are known in the art. Therefore, the disclosure of this means in FIG. 1comprises a simple hydraulic cylinder 60 having a piston 61 connected toa hanger and sealing member 62 from which the macaroni 22 is suspended.

While the invention has been disclosed in conjunction with a specificform and disposition of the parts, it should be expressly understoodthat numerous modifications and changes may be made without departingfrom the spirit and scope of the appended claims.

What I claim is:

1. In a fluid actuated downwell pump installation including a welltubing in which a fluid actuated pump is seated and a separate string ofsmaller tubing within said first tubing, said first tubing beingnormally connected to receive power oil for said pump unit in theannulus around said separate tubing, and said separate tubing beingnormally connected to receive fluid produced by said pump unit, theimprovement comprising means to open said separate tubing for thereception of a soluble clean-out plug, valve means at the surface toconnect said separate tubing to receive power oil and said first tubingto exhaust, whereby contaminants are removed from the interior of saidseparate tubing by forcing said soluble plug down under the pressure ofpower oil, and normally closed valve means disposed adjacent said pumpunit openable by pressure in said separate tubing in the direction ofsaid first tubing to interconnect said first and separate tubing stringsto bypass fluid and contaminants forced from said separate tubing bysaid soluble plug.

2. In a fluid actuated downwell pump installation including a welltubing in which a fluid actuated pump unit is seated and a separatestring of smaller tubing within said first tubing, said pump unit beingconnected to said separate string of smaller tubing, said first tubingbeing normally connected to receive power oil from a pump into theannulus around said separate tubing, and said separate string of tubingbeing normally connected to receive fluid produced by said pump unit,the improvements comprising a jack means at the surface connected toraise said separate tubing in said first tubing and said pump unit fromits seat while maintaining the flow of power oil in said first tubing,whereby power oil flows through said pump unit in a direction normallytaken by pumped production fluid.

References Cited in the file of this patent UNITED STATES PATENTS1,723,162 Harris Aug. 6, 1929 2,194,740 Coberly Mar. 26, 1940 2,230,830Coberly Feb. 4, 1941 2,411,044 Landrum et al. Nov. 12, 1946 2,663,261Gage Dec. 22, 1953 2,980,027 Dulaney Apr. 18, 1961

1. IN A FLUID ACTUATED DOWNWELL PUMP INSTALLATION INCLUDING A WELLTUBING IN WHICH A FLUID ACTUATED PUMP IS SEATED AND A SEPARATE STRING OFSMALLER TUBING WITHIN SAID FIRST TUBING, SAID FIRST TUBING BEINGNORMALLY CONNECTED TO RECEIVE POWER OIL FOR SAID PUMP UNIT IN THEANNULUS AROUND SAID SEPARATE TUBING, AND SAID SEPARATE TUBING BEINGNORMALLY CONNECTED TO RECEIVE FLUID PRODUCED BY SAID PUMP UNIT, THEIMPROVEMENT COMPRISING MEANS TO OPEN SAID SEPARATE TUBING FOR THERECEPTION OF A SOLUBLE CLEAN-OUT PLUG, VALVE MEANS AT THE SURFACE TOCONNECT SAID SEPARATE TUBING TO RECEIVE POWER OIL AND SAID FIRST TUBINGTO EXHAUST, WHEREBY CONTAMINANTS ARE REMOVED FROM THE INTERIOR OF SAIDSEPARATE TUBING BY FORCING SAID SOLUBLE PLUG DOWN UNDER THE PRESSURE OFPOWER OIL, AND NORMALLY CLOSED VALVE MEANS DISPOSED ADJACENT SAID PUMPUNIT OPENABLE BY PRESSURE IN SAID SEPARATE TUBING IN THE DIRECTION OFSAID FIRST TUBING TO